After setting up my iPhone last week, I found that there were some touch screen calibration issues - I couldn't touch the setup icon in the Koi Pond application - the screen ended before the point where the application wanted me to touch.
Thanks to a rather Apple saturated home, and installing the TouchTrain application on another iPhone and a Touch, my iPhone clearly showed it was registering touches about 5-10 pixels above where you actually touched.
A genius at the new Apple store in Chadstone happily handed over a replacement after a demonstration, and after setting it up and restoring it from a previous backup of my 'old' iPhone under Windows, the replacement also showed the same problem.
Setting up the 'new' iPhone as a new phone (not restoring it from a previous backup), fixed the problem. (Hmmm.... my electonic-disrupting field has been working overtime recently...)
My theory, is that the original backup 'image' was from a Touch, which had been trained or calibrated to my typing style. I had backed up my contacts to a Mac version of iTunes, and happily these made it back onto the new phone without affecting the touch calibration. If anyone knows the real reason why this problem occurred, I'd love to know!